1. Field of Invention
The present invention relates to an electric wiring construction having a bus bar that supplies electricity to one or more electrical components. A first connection terminal is connected with the bus bar by means of a first screw tightened into the bus bar. A second connection terminal is connected with the bus bar by means of a second screw tightened into the bus bar. An input line is connected with the first connection terminal, and an output line that supplies electric current to one or more other electricity-consuming components is connected with the second connection terminal.
2. Description of Related Art
Conventionally, the various electricity-consuming components installed on a vehicle (e.g. a glow plug, heater, or the like) are powered by electricity generated by a generator which is operated by the actuation of the engine. A relay box is provided on an electricity supply path connected with the electricity-consuming components. The relay box accommodates a plurality of relays that switches the supply of electric current to electricity-consuming components, to turn them on and off. FIG. 6 shows a conventional relay box 11. An electrically conductive bus bar 12 is installed on the relay box 11. Relays are electrically connected with the bus bar 12. A part of the bus bar 12 is exposed on an outer surface of the relay box 11. Electricity generated by a generator is transmitted to the relays through an input line 13 and the bus bar 12. The input line 13 is crimped to connect it with a first crimping portion 151 of a first connection terminal 15. The first connection terminal 15 is connected with the bus bar 12 by a first screw 16 tightened into the bus bar 12.
The bus bar 12 that supplies electricity to the relays is also used to supply electricity to other electricity-consuming components other than via the relays. An output line 14 that supplies electricity to the other electricity-consuming components is crimped to connect it with a second crimping portion 171 of a second connection terminal 17. The second connection terminal 17 is connected with the bus bar 12 by a second screw 18 tightened into the bus bar 12.
The electricity generated by the generator is transmitted to the relays accommodated inside the relay box 11 and the output line 14 through the input line 13 and the bus bar 12. That is, through the bus bar 12, electricity is sent to the other electricity-consuming components positioned at the other end of the output line 14. When electricity passes through the bus bar 12, heat is generated by the bus bar 12. The generated heat is transmitted to the first and second connection terminals 15 and 17 and the first and second screws 16 and 18. Owing to the heat transmission, the first and second connection terminals 15 and 17 and the first and second screws 16 and 18 are heated. As described above, the input line 13 is fixed by crimping to the first connection terminal 15, and the output line 14 is fixed by crimping to the second connection terminal 17. When the temperature of the generated heat of the bus bar 12 exceeds the thermal resistance temperature of the first connection terminal 15 and that of the second connection terminal 17, the electrical contact between the input line 13 and the first crimping portion 151 and that between the output line 14 and the second crimping portion 171 become poor.